The recent surge in popularity of portable phones, laptops, PDAs, and tablet-based computer processing devices, such as the iPad™, Xoom™, Galaxy Tab™ and Playbook™ has spurred new dimensions of personal computing. Often referred to a “portable computing devices,” these devices often include interfaces, such as touch screens, miniature/portable keyboards and other peripherals that allow users to input and receive data just as they would on stationary personal computers (PC). One aspect of portable computing devices that has received recent attention is the use of accelerometers in portable computing devices. Generally speaking, an accelerometer is a sensor that measures acceleration of a device, where the acceleration is attributed either to motion or gravity. Acceleration can be generated using static forces such as a constant force of gravity, or dynamic forces such as moving or vibrating a device.
One example of includes the LIS331DL 3-axis accelerometer manufactured by STMicroelectronics, which is a small, low-power linear accelerometer. The device features digital I2C/SPI serial interface standard output and smart embedded functions. The sensing element, capable of detecting the acceleration, is manufactured to produce inertial sensors and actuators in silicon. The IC interface is manufactured using a CMOS process that provides a dedicated circuit which is trimmed to better match the sensing element characteristics. The LIS331DL has dynamically user selectable full scales of ±2 g/±8 g and it is capable of measuring accelerations with an output data rate of 100 Hz or 400 Hz. Those skilled in the art recognize that the above is only one example and that a multitude of other accelerometers from various manufacturers are suitable for the present disclosure.
Accelerometers, and in some cases magnetometers, are becoming widely accepted as a useful tool for measuring human motion in relation to a portable computing device. Accelerometers offer several advantages in monitoring of human movement, in that the response to both frequency and intensity of movement makes them superior to actometers or pedometers. Also, accelerometers do not require the computing power of the portable computing device in the sensing process. The piezoelectric or MEMS (Micro-Electromechanical System) sensors in accelerometers are actually sensing movement accelerations and the magnitude of gravitational field.
Portable computing devices are also becoming popular candidates for audience measurement purposes. In addition to measuring on-line media usage, such as web pages, programs and files, portable computing devices are particularly suited for surveys and questionnaires. Furthermore, by utilizing specialized microphones, portable computing devices may be used for monitoring user exposure to media data, such as radio and television broadcasts, streaming audio and/or video, billboards, products, and so on. Some examples of such applications are described in U.S. patent application Ser. No. 12/246,225, titled “Gathering Research Data” to Joan Fitzgerald et al., U.S. patent application Ser. No. 11/643,128, titled “Methods and Systems for Conducting Research Operations” to Gopalakrishnan et al., and U.S. patent application Ser. No. 11/643,360, titled “Methods and Systems for Conducting Research Operations” to Flanagan, III et al., each of which are assigned to the assignee of the present application and are incorporated by reference in their entirety herein.
One area of audience measurement in the area of portable computing devices requiring improvement is the area of user identification, particularly in the area of portable computing devices equipped with accelerometers. What are needed are systems and methods that allow a portable computing device to collect and process accelerometer data to allow recognition of a particular user, and to register physical activity (or inactivity) associated with a user when media exposure (e.g., viewing web page, viewing or listening to a broadcast or streaming media) is taking place. To accomplish this, accelerometer profiles are needed that uniquely identifies each user and certain physical activity. Additionally, the accelerometer profiles may be used to determine if a non-registered person is using the device at a particular time. Such configurations are advantageous in that they provide a non-intrusive means for identifying users according to their physical activity, inactivity or a combination of both, instead of relying on data inputs provided by a user at the beginning of a media session, which may or may not correlate to the user actually using the device.
Additionally, accelerometer data may be useful in detecting device compliance to determine if users or panelists are correctly using portable metering devices and/or if multiple devices are being carried. Often times, users and/or panelists can carry multiple devices, which may lead to inaccurate media measurement results. It would be advantageous to use accelerometer data to identify such phenomena when they occur.